Patient specific quality assurance (QA) in MR-Linacs can be performed with MR-compatible ion chamber arrays. However, the presence of a static magnetic field can alter the angular response of such ...arrays substantially. This works investigates the suitability of two ion chamber arrays, an air-filled and a liquid-filled array, for patient specific QA at a 0.35 T MR-Linac using a static phantom.
In order to study the angular response, the two arrays were placed in a static, solid phantom and irradiated with 9.96 × 9.96 cm
fields every 10° beam angle at a 0.35 T MR-Linac. Measurements were compared to the TPS calculated dose in terms of gamma passing rate and relative dose to the central chamber. 20 patient specific quality assurance plans were measured using the liquid-filled array.
The air-filled array showed asymmetric angular response changes of central chamber dose of up to 18% and down to local 3 mm / 3% gamma rates of 20%, while only minor differences within 3% (excluding parallel irradiation and beams through the couch edges) were found for the liquid-filled ion chamber array without rotating the phantom. Patient plan QA using the liquid-filled array yielded a median local 3 mm / 3% 3D gamma passing rate of 99.8% (range 96.9%-100%).
A liquid-filled ionization chamber array in combination with a static phantom can be used for efficient patient specific plan QA in a single measurement set-up in a 0.35 T MR-Linac, while the air-filled ion chamber array phantom shows large angular response changes and has its limitations regarding patient specific QA measurements.
•Smartphone apps for behaviour change enable social innovation in the short-term.•Conditions outside of projects impact long-term behaviour change and growth in app users.•Behaviour change apps ...should be assessed beyond the short-term as a policy instrument.
Digital tools, specifically smartphone apps, have emerged as enablers of social innovation for low-carbon transitions by using novel feedback to creatively engage people to act more sustainably, and thus capture the power of collective individual action. Such apps have increasingly been implemented in real-world experiments with positive results in the short-term. However critical reflection is required to look beyond this hype to understand the conditions for longer term impact, thus reaching a transformative social innovation potential. In this paper, we take two exemplary behaviour change apps and perform a cost-benefit analysis to assess the break-even point in number of users to achieve net-positive impact and discuss relevant technical, organisational, political and financial conditions that enable or impede this impact. We find that the required scale-up in users seems challenging, yet feasible. However, guaranteeing that the supportive conditions are available is necessary to warrant the focus on behaviour change apps by research and policy.
We present an extensive experimental study of the recently predicted pygmy quadrupole resonance (PQR) in Sn isotopes, where complementary probes were used. In this study, (α,α′γ) and (γ,γ′) ...experiments were performed on 124Sn. In both reactions, Jπ=2+ states below an excitation energy of 5 MeV were populated. The E2 strength integrated over the full transition densities could be extracted from the (γ,γ′) experiment, while the (α,α′γ) experiment at the chosen kinematics strongly favors the excitation of surface modes because of the strong α-particle absorption in the nuclear interior. The excitation of such modes is in accordance with the quadrupole-type oscillation of the neutron skin predicted by a microscopic approach based on self-consistent density functional theory and the quasiparticle-phonon model (QPM). The newly determined γ-decay branching ratios hint at a non-statistical character of the E2 strength, as it has also been recently pointed out for the case of the pygmy dipole resonance (PDR). This allows us to distinguish between PQR-type and multiphonon excitations and, consequently, supports the recent first experimental indications of a PQR in 124Sn.
Structure-integrated force measurement in hexapod structures or kinematics offers great potential for spatial process force control in six degrees of freedom. Although force control has been studied ...for many years, research questions remain unanswered, especially when regarding parallel kinematic machine tools with numerical control and integrated sensors. This contribution summarizes the technology of structure-integrated force sensing in hexapod machine tools and develops two approaches to use the measured signals for direct hybrid/parallel force control. For different use-cases, such as teach-in or synchronous force/position control with variable task frame, different approaches of set-point specification and injection of manipulated values are studied from a practical point of view. As a result of the work, the feasibility of the force control with structure-integrated sensors on a commercial CNC can be confirmed through appropriate experiments. Furthermore, the realized G-Code integration represents a practical solution for programming force-controlled machine tools in an easy and concise way from the NC programme.
Continuous high‐intensity mixing of two fluids for carrying out fast precipitation is an important method for producing nanoparticulate solids for diverse applications, e.g., in fine chemistry, ...pigment or catalyst preparation. Continuous precipitation with a newly developed micromixer technology, the so‐called valve‐assisted micromixer, allows for stable operation without clogging for several days. Scale‐up to technically relevant scale was achieved without differences in the quality of the precipitate. The technology has been extensively tested for preparation of catalysts for production of carbon nanotubes.
A modular continuous precipitation unit was developed, based on a novel valve‐assisted micromixer. Scale‐up of the micromixer was realized from laboratory to technically relevant scale. The unit was applied for carbon nanotubes catalyst manufacturing. The catalyst prepared by this process was superior with respect to catalyst and product quality compared to a batch process.
The composition of silica-supported copper (II) chloride substances for the oxychlorination of carbon monoxide to phosgene was optimized systematically here. When the molar ratio of Cu:K
=
5:1 and ...the surface area of SiO
2 is 25
m
2
g
−1, the substance 30Cu:6K/SiO
2-1 can be used eight times, and the cumulative yield of phosgene is up to 89.6%.
In this work, we checked the influences of the silica-supported copper (II) chloride substance composition on the oxychlorination of CO to phosgene. The effects of the content of copper (II) chloride, the ratio of copper to potassium, the different kinds of promoters, like sodium chloride, potassium chloride and caesium chloride, and the surface area of silica gel were systematically investigated. The lower surface area of the support can contribute to the formation of phosgene while the higher surface area of the support can lead to a rather low yield of phosgene. The reaction activity of silica-supported copper (II) chloride substance increases with the content of copper chloride (within 30
wt.%). However, in order to avoid the agglomeration of the substance, the content of copper chloride should be less than 30
wt.%. The optimized molar ratio of CuCl
2 to KCl is 5:1. Of all three promoters, NaCl, KCl and CsCl, CsCl or KCl can function better than NaCl due to the stronger Lewis basicity. The molten phase can remarkably improve the contact of CuCl
2 and CO. On the whole, the lower-surface-area support, the higher content of CuCl
2 and the promoter CsCl or KCl are prefered in the oxychlorination of CO.
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